1. Field of the Invention
Implementations of various technologies described herein generally relate to seismic data processing.
2. Description of the Related Art
The following descriptions and examples are not admitted to be prior art by virtue of their inclusion within this section.
In a typical seismic survey, a plurality of seismic sources, such as explosives, vibrators, airguns or the like, may be sequentially activated at or near the surface of the earth to generate energy which may propagate into and through the earth. The seismic waves may be reflected back by geological formations within the earth. The resultant seismic wavefield may be sampled by a plurality of seismic sensors, such as geophones, hydrophones and the like. Each sensor may be configured to acquire seismic data at the sensor's location, normally in the form of a seismogram representing the value of some characteristic of the seismic wavefield against time. A seismogram may also be commonly known as a seismic trace. The acquired seismograms may be transmitted wirelessly or over electrical or optical cables to a recorder system. The recorder system may then store, analyze, and/or transmit the seismograms. This data may be used to detect the possible presence of hydrocarbons, changes in the subsurface and the like.
Seismograms may contain unwanted signals, or noise, as well as the desired seismic reflection signals. Unwanted signals may interfere with the interpretation of the seismic signals and degrade the quality of the subsurface images obtained by processing the recorded seismograms. It may therefore be desirable to suppress or attenuate the unwanted signal that may be present in the recorded seismograms during processing. Various techniques have been developed to process seismograms in an effort to amplify the seismic reflection signals and attenuate the unwanted signals, such as semblance spectrum velocity analysis, normal moveout (NMO) correction, NMO stacking and the like. Other common techniques used to process seismograms include tools to manipulate travel times in seismograms. Deconvolution, also referred to as spectral division, may be one such tool. After deconvolution, the seismic data may be recorded according to travel time difference rather than travel time.
In the field of interferometry, seismograms may be converted into seismic interferograms by deconvolving two seismograms that have been transformed from the time domain into the frequency domain. This process combines the two seismograms into one seismic interferogram that contains the difference between the two seismograms, cancelling out all that may be in common between the seismograms such as unwanted signals.
Typical techniques applied during seismic data processing may not adequately amplify the reflection signal and attenuate the unwanted signal. Accordingly, improved methods for processing seismic data may be desirable. Using interferometry techniques combined with typical seismic data processing techniques may improve various methods for processing seismic data.